asMimeHeaderAttribute
Casts this RuleStringToEvaluate as a MimeHeaderAttribute and retrieves its kotlin.String value. Throws an exception if the RuleStringToEvaluate is not a MimeHeaderAttribute.
Casts this RuleStringToEvaluate as a MimeHeaderAttribute and retrieves its kotlin.String value. Throws an exception if the RuleStringToEvaluate is not a MimeHeaderAttribute.